戴维·努南
Social change—from evolving attitudes toward gender and marijuana to the rise of Donald Trump to the emergence of the Black Lives Matter and #MeToo movements2—is a constant3. It is also mysterious, or so it can seem. For example, “How exactly did we get here?” might be asked by anyone who lived through decades of fierce prohibition and now buys pot4 at one of the more than 2,000 licensed dispensaries across the U.S.
A new study about the power of committed minorities to shift conventional thinking offers some surprising possible answers. Published this week in Science5 the paper describes an online experiment in which researchers sought to determine what percentage of total population a minority needs to reach the critical mass necessary to reverse a majority viewpoint. The tipping point, they found, is just 25 percent. At and slightly above that level, contrarians6 were able to “convert” anywhere from 72 to 100 percent of the population of their respective groups. Prior to the efforts of the minority, the population had been in 100 percent agreement about their original position.
The experiment was designed and led by Damon Centola, associate professor in the Annenberg School of Communications at the University of Pennsylvania. It involved 194 people randomly assigned to 10 “independent online groups,” which varied in size from 20 to 30 people. In the first step group members were shown an image of a face and told to name it. They interacted with one another in rotating pairs until they all agreed on a name. In the second step Centola and his colleagues seeded each group with “a small number of confederates… who attempted to overturn the established convention (the agreed-on name) by advancing a novel alternative.”
For the second step, as Centola explains it, the researchers began with a 15 percent minority model and gradually increased it to 35 percent. Nothing changed at 15 percent, and the established norm remained in place all the way up to 24 percent.
The magic number, the tipping point, turned out to be 25 percent. Minority groups smaller than that converted, on average, just 6 percent of the population. Among other things, Centola says, that 25 percent figure refutes a century of economic theory. “The classic economic model—the main thing we are responding to with this study—basically says that once an equilibrium is established, in order to change it you need 51 percent. And what these results say is no, a small minority can be really effective, even when people resist the minority view.” The team’s computer modeling indicated a 25 percent minority would retain its power to reverse social convention for populations as large as 100,000.
But the proportion has to be just right: One of the groups in the study consisted of 20 members, with four contrarians. Another group had 20 members and five contrarians—and that one extra person made all the difference. “In the group with four, nothing happens,” Centola says, “and with five you get complete conversion to the alternative norm.” The five, neatly enough, represented 25 percent of the group population.
Real-life factors that can work against committed minorities—even when they reach or exceed critical mass—include a lack of interaction with other members, as well as competing committed minorities and what’s called “active resistance”—which pretty well describes the way many people in 2018 respond to political ideas with which they disagree. But even with such obstacles, Centola says the tipping point predicted in his model remains well below 50 percent.
Certain settings lend themselves to7 the group dynamics Centola describes in his study, and that includes the workplace. “Businesses are really great for this kind of thing,” he says, “because people in firms spend most of their day trying to coordinate with other people, and they exhibit the conventions that other people exhibit because they want to show that they’re good workers and members of the firm. So you can see very strong effects of a minority group committed to changing the culture of the population.”
The other environment in which the 25 percent effect is particularly evident, Centola says, is online—where people have large numbers of interactions with lots of other people, many of them strangers. This raises some tricky questions: Can a bot8 stand in for a member of a committed minority? And can a committed minority be composed of bots and the real people the bots influence, so that bots are actually driving the change? According to Centola, “In a space where people can’t distinguish people from bots, yes. If you get a concerted, focused effort by a group of agents acting as a minority view, they can be really effective.”
Yale sociologist Emily Erikson, who also studies social networks but was not involved with the study, sees the new paper partly as a warning. “In some sense it’s saying extreme voices can quickly take over public discourse,” she says. “Perhaps if we’re aware of that fact, we can guard against it.”
從对性别问题和对大麻的态度变化到特朗普崛起,乃至“黑命贵”运动和#MeToo反性侵运动,社会变化已成常态。社会变化也神秘莫测,或者说似乎如此。例如,几十年间一直严禁大麻,而现在可以在分布于美国各地的2000多家特许药房购买,任何经历这一变化的人都可能会问:“我们到底是如何变成这样的?”
有一项关于意志坚定的少数人具备改变传统思维的新研究,可能提出了一些令人惊讶的答案。该研究发表在本周的《科学》杂志上。论文中描述了一次网络实验,在实验中,研究人员力求确定少数人至少占总人群的多大比例就足以逆转多数人观点。他们发现,这个临界点仅为25%。当持反对观点者占或略高于总数的25%时,便能转变他们各自小组中72%至100%的人的观点。在少数人发挥影响力之前,小组成员百分之百认同他们原先的立场。
该实验由宾夕法尼亚大学阿能伯格传播学院副教授戴蒙·森托拉设计和主持。参与实验的194人被随机分成10个“独立网络小组”,各组人数为20至30人不等。实验第一步,给各组成员看一张人脸,并要求他们为之取名;组内成员两两配对进行互动,然后轮换搭档,直到全部成员达成共识。第二步,森托拉和同事们在每一组中植入“为数不多的同谋者……这些人提出一个新名字,以推翻小组既有的约定(即原已达成共识的名字)。”
森托拉解释说,在第二步中,研究人员最初植入15%的少数人,然后逐渐增加到35%。少数人占15%时,情况毫无变化;直到比例升至24%,既有约定依然如故。
实验发现,这个神奇的比例或临界点是25%。少数人低于25%时,他们平均只能转变6%的人。森托拉说,发现25%这个比例的价值之一是,它驳倒了一个历时百年的经济理论。“本研究主要针对一个古典经济模型。该模型的基本论点是,均衡状态一经形成,需要51%的反作用力才能将其改变。然而,这些实验结果说明,事实并非如此。实际上,小比例的少数人也会起很大的作用,即使在人们抵制其观点的情况下。”森托拉团队的计算机模型表明,在多达10万的人群中,25%的少数人仍具有逆转社会常规的能力。
但这个比例必须恰到好处:参加此研究的一组有20名成员和4名持反对观点者,另一组有20名成员和5名持反对观点者,而正是那1人之差起了关键作用。森托拉说:“在有4名持反对观点者的小组中,情况没有变化;但有5名反对者时,所有成员都一致转而同意反方观点。”5这个数字,不多不少,恰好是小组人数的25%。
坚定的少数即使达到或超出临界点,也有可能受阻于种种现实因素,包括缺乏与其他成员的互动、来自其他坚定少数派的竞争以及所谓的“积极抵制”因素(“积极抵制”很好地描述了2018年许多人面对他们不认同的政治观念时的回应方式)。但森托拉认为,即使存在这些阻碍,他的模型所预测的临界点仍然远远低于50%。
某些特定的环境易于发生森托拉在其研究中所描述的小组动态,例如职场。“企业就是很好的例子。”森托拉说,“公司员工一天中大部分时间都在努力与其他人协调。为了表明自己是公司的好员工、好成员,他们显示出与公司其他人同样的习惯。因此,努力想改变群体文化的少数派的影响会显得特别强烈。”
森托拉说,网络也是25%效应尤为明显的环境。网上人与人之間有大量的互动,而且大多发生在陌生人之间。这就产生了一些棘手的问题:某个机器人会不会替代坚定少数派的某个成员?坚定的少数人会不会是由机器人和受机器人影响的真人组成,结果实际上是机器人在驱动改变?森托拉认为:“在人们无法区分真人与机器人的网络空间里,答案是肯定的。如果你能让一群代言者同心协力主张少数人的观点,他们很可能会大有成效。”
同样研究社交网络但并未参与此项研究的耶鲁大学社会学家埃米莉·埃里克松认为,这篇新论文在一定程度上是一个警告。她说:“在某种意义上,该论文在警示我们,极端的声音可能会迅速取代公共话语。如果我们意识到这个事实,也许能够防患于未然。”
(译者单位:北京第二外国语学院)